Alderfen Broad is a 21.3-hectare (53-acre) biological Site of Special Scientific Interest north-east of Norwich in Norfolk, England.

[1][2] It is managed by the Norfolk Wildlife Trust.

[3] It is part of the Broadland Ramsar site[4] and Special Protection Area[5] and The Broads Special Area of Conservation.

[6] This area of fenland peat has open water, alder carr woodland and reedswamp.

Breeding birds include the great crested grebe, water rail, grasshopper warbler and reed warbler.